Digital nuclear control rod control system

Abstract

A digital rod control system that employs separate power modules to energize the respective coils of a magnetic jack control rod drive rod drive system so that two, independently powered grippers can simultaneously support the control rod drive rod when it is not in motion to avoid dropped rods. The basic building block of the system is two or more selecting cabinets which receive multiplex power from at least one moving cabinet and are under the control of a single logic cabinet. Each of the cabinets include monitoring features to confirm the reliability of the system.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to Provisional Application Ser. No. 61 / 229,460, filed Jul. 29, 2009, entitled DIGITAL ROD CONTROL SYSTEM.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates in general to nuclear reactor control systems and, in particular, to systems for controlling the movement of nuclear control rods into and out of the core of a nuclear reactor.[0004]2. Description of the Prior Art[0005]In a nuclear reactor for power generation, such as a pressurized water reactor, heat is generated by fission of a nuclear fuel such as enriched uranium, and transferred into a coolant flowing through a reactor core. The core contains elongated nuclear fuel rods mounted in proximity with one another in a fuel assembly structure through and over which the coolant flows. The fuel rods are spaced from one another in co-extensive parallel arrays. Some of the neutrons and other atomic particles released durin...

AI Technical Summary

Benefits of technology

The nuclear control rod control system described in this patent is designed to control the movement of multiple drive rod systems in a nuclear reactor. The system includes a logic unit that coordinates electrical power to the lift coils, moveable grippers, and stationary grippers of the control rod drive systems. The system also includes a moving unit that controls the electrical power to the lift coils in at least two selecting units, which control the movement of control rod assemblies in groups. Each selecting unit controls at least two groups of control rod assemblies, and the moveable grippers and stationary grippers in each control rod assembly move together in a coordinated manner. The system also includes a current regulator controller that monitors and controls the current in each coil and gripper, and a fault protection system that identifies and isolates faults in the power control modules. The selecting units can also energize the moveable and stationary grippers in the same control rod assembly when the lift coils are not energized. Overall, the system provides precise control and monitoring of the movement of the control rod assemblies in a nuclear reactor.

Problems solved by technology

Inserting a control rod further into the core causes more neutrons to be absorbed without contributing to fission in an adjacent fuel rod; and retracting the control rod reduces the extent of neutron absorption and increases the rate of the nuclear reaction and the power output of the core.

These systems have many single failure mechanisms any one of which can lead to dropped rods.

The systems were designed prior to, and do not take advantage of, the capabilities of modern computer-based instrumentation and control equipment.

Furthermore, these systems are costly to manufacture and maintain and an improved rod control system that overcomes these and other limitations is needed.

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